from __future__ import annotations

import tempfile
from pathlib import Path

from fastapi import APIRouter, HTTPException, UploadFile

from app.config import settings
from app.services.batch import process_batch

router = APIRouter()

ALLOWED_EXTENSIONS = {".pdf", ".xlsx", ".xls", ".csv"}


@router.post("/upload")
async def upload_files(files: list[UploadFile]):
    if not files:
        raise HTTPException(400, "No files provided")

    saved: list[Path] = []
    tmp_dir = Path(tempfile.mkdtemp(prefix="cmm_"))

    for f in files:
        if not f.filename:
            continue
        ext = Path(f.filename).suffix.lower()
        if ext not in ALLOWED_EXTENSIONS:
            raise HTTPException(
                400, f"Unsupported file type: {ext}. Allowed: {ALLOWED_EXTENSIONS}"
            )
        size = 0
        dest = tmp_dir / f.filename
        with open(dest, "wb") as out:
            while chunk := await f.read(1024 * 64):
                size += len(chunk)
                if size > settings.max_upload_mb * 1024 * 1024:
                    raise HTTPException(400, f"File too large (max {settings.max_upload_mb} MB)")
                out.write(chunk)
        saved.append(dest)

    if not saved:
        raise HTTPException(400, "No valid files uploaded")

    batch_id = await process_batch(saved)
    return {"batch_id": batch_id, "file_count": len(saved)}